In general, lithium-ion (Li-ion) batteries are principally used in consumer electronic devices such as lap top computers, cell phones, cameras, camcorders, and MP3 players. Li-ion batteries used in the above-mentioned devices can be made in a single electrochemical cell or multiple cells in series or parallel, depending upon power consumption needs. Lap top computer batteries usually include four to nine individual cells per pack. The cells used in these devices are typically small in capacity (<2 ampere hour (“Ah”) typically). Cells used in consumer electronic devices are typically of a wound-electrode configuration. The structure is a long narrow structure having separator layers and electrode layers (cathode and anode layers) spiraled on a mandrel, forming a “jelly roll” structure. The jelly roll can be processed in the following ways:                a. The jelly roll may be a tight spiral that is subsequently placed in a cylindrical can for further processing—i.e. 18650 and 26650 standard size round cells used in lap top computers and power tools. Here, “18” means that the can is 18 mm in diameter, and “65” means that the can is 65 mm in height. “0” has no meaning here.        b. The jelly roll may be a compressed, flattened jelly roll that is subsequently placed in a plastic pack as is typically used in cell phone batteries, MP3 players and like-sized devices.        
The wound format lends itself to rapid construction of the electrode/separator mass and large scale automation of the fabrication process. Typically, the electrode/separator mass can be wound in a few seconds (approximately 2 seconds). A single automated machine can construct millions of these cell structures in a typical operation over a short period of time. To date, 18650 and 26650 wound Li-ion cells are produced in large quantities, typically characterized by an electrochemical capacity often less than 4 Ah, depending on cell design and the electrode material chosen.
The wound cell design for large capacity power needs is not practical for a few reasons, including: (1) the processing practicality to maintain concentricity of all the wound electrodes; and (2) safety concerns due to thermal management issues when the battery is in a high rate charge or discharge mode.
While cells of less than 4 Ah capacity are typically of a wound-based construction, the large capacity cells (“large format” cells) are of a stacked construction. In this format, the electrode/separator mass includes a number of alternating layers of separator, then cathode (or anode) electrode, then separator, then anode (or cathode) electrode. This stacking arrangement can be repeated a number of times (for example, 50 times) to reach the desired cell capacity according to the cell design and specification.
Current processes for stacking large format cells depend on manual hand stacking or the use of a stacking machine that accommodates provisions for the automatic laying of the alternate layers of the electrode/separator mass. Typically each cathode and anode electrode sheet is cut to its size and shape in a separate process. Due to its thinness and propensity to acquire a static electrical charge during handling, an automatic machine provides a means to cut or fold the separator material (e.g., Z fold) as part of the stacking process to minimize handling. The electrode sheets are placed onto their respective alternating layers using a pick-and-place technique, whereby a single machine will pick up a single electrode layer and deposit it upon the cell stack. Typically the electrode is held onto the pick-up machine via a reduced air pressure (vacuum) applied at the point of contact of the machine and the electrode surface. The action of picking-up and depositing an electrode upon the stack occurs over the course of a few seconds (about 2 to about 5). In the case of a typical 25 composite electrode layer cell, the stacking will take from about 2 to about 5 minutes to complete.
An automated manufacturing system for a layered cell having an improved structure and a manufacturing process that simplifies and enhances assembling efficiency in a continuous process is needed.